Dimers of hexafluoropropene and propylene

ABSTRACT

Cis and trans-1-trifluoromethyl-1,2,2-trifluoro-4-methylcyclobutane and mixtures thereof are provided. These compositions are liquids having high dielectric constant and low freezing points, useful as working fluids for hydraulic systems and as inert solvents. Also provided are linear dimers, 4,4,5,6,6,6hexafluorohexene-1 and 4,4,5,6,6,6-hexafluorohexene-2, useful as co-monomers in ethylene and propylene polymerization.

United States Patent LaLande, Jr. et al.

[ Jan. 29, 1974 DIMERS OF HEXAFLUOROPROPENE AND PROPYLENE Inventors:William Alfred LaLande, Jr.,

Philadelphia; Murray Hauptschein, Glenside; Robert Bonner Hagar,Collegeville, all of Pa.

Pennwalt Corporation, Philadelphia, Pa.

Filed: May 24, 1971 Appl. No.: 146,503

Assignee:

US. Cl. 260/648 F, 260/6533, 252/73,

252/66, 252/364 Int. Cl. C07c 23/06 Field of Search 260/648 F ReferencesCited UNITED STATES PATENTS 5/1972 Hutchinson 260/6533 PrimaryExaminer-Daniel D. Horwitz Attorney, Agent, or Firm-Stanley Litz [57]ABSTRACT 2 Claims, No Drawings DIMERS OF HEXAFLUOROPROPENE AND PROPYLENEThe compositions of this invention are a mixture of cis-and trans- 1-trifluoromethyll ,2,2-trifluoro-4- methylcyclobutane, referred to asthe mixed cyclic dimer or 1:1 cycloadducts of hexafluoropropene andpropylene, the individual cyclic dimers, and the 1:1 linear adducts (orlinear dimers) 4,4,5,6,6,6-hexafluorohexene-l and4,4,5,6,6,6-hexafluorohexene-2. These new compounds are produced by thethermallypromoted reaction of hexafluoropropene and propylene.

The cyclic compositions of this invention, trifluoromethyl-1,2,2-trifluoro-4-methylcyclobutane,

are produced as a mixture of the cis-isomer C-.C H i H I be. I

H CH

and the trans-isomer l (I yr wherein the ratio of cis:trans lsomer maybe in the range of about 5:95 to 95:5. The individual cis and transisomers can be isolated by gas chromatography separation techniques wellknown to those skilled in the art.

The hexafluoropropene-propene cyclic adducts embodied herein havecertain unexpected physical characteristics which distinguish them fromsuperficially structurally similar products, giving the new products awider range of utility, including new and diverse uses. Their valuableand distinguishing properties are noted when compared to the cyclicdimer of hexafluoropropene (perfluorodimethylcyclobutane) disclosed inUS. Pats. No. 2,957,032 and No. 3,316,312, and the cyclic dimer oftetrafluoroethylene and propylene l-methyl-2,2,3,3-tetrafluorocyclobutane) described by DD. Coffman et al., J.Am.Chem. Soc. 71, pp. 490-96 1949). These differences are discussed in moredetail later in this specification.

The compounds of this invention are prepared by bringing together themonomers hexafluoropropene and propylene. in mole ratios within therange of about 1:1 to 1:20, at reaction temperatures of from about 200C.to about 800C, preferably from 240 to 350C. Reaction pressures can varyfrom one to about 500 atmospheres. but prefereably will be in the rangeof 50 to 200 atmospheres. The reaction may be carried out eithercontinuously in a hot tube flow system or batchwise in a pressurevessel. Performing the reaction at lower temperatures, e.g., on theorder of about C, using di-tertiary-butyl peroxide as a catalyst, willfavor the production of more of the linear, terminally unsalw ratedadduct.

The invention is clarified by the following illustrative example.

To a 2-gall0n stainless steel, stirred autoclave cooled in a DryIce/acetone bath are charged 1,755 g. l 17 moles) of perfluoropropeneand 905 g. (21.5 moles) of propylene. The autoclave is sealed and heatedfor 24 hours at 250C. with stirring. After cooling to room temperature,1,631 g. of liquid and 906 g. of gas are recovered. Distillation of theliquid gives 1,361 g. (59% conversion) of the mixed dimer product ofthis invention. Mass spectral analysis shows the molecular weight to be192, consistent with the stated structure. F n.m.r. analysis gives thefollowing data (expressed as ppm. from trifluoroacetic acfi).

lsomer CF CFZ F trans +2.96 24.56. 28.36, 29.59, 33.4 1 16.5 cis 7 7i lali. 3 AAQL 9 4- which is consistent with the structure given. The CFbands are AB quartets with a geminal coupling constant of about 215 Hz.Infrared analysis shows absorbance as follows: lsomer Bands trans 3.3lw,3.34w, 339w, 3.45w, 6.75w, 68w. 7.25m, 7.5m, 7.6m, S.lm, 8.2ls, 8.42s,l0.2m, 10.5w, 13.5w, 15.6w microns cis 3.3lw, 3.34w, 3.39w, 3.45w,6.75w, 6.8w, 725w, 7.5m, 7.6m, 8.1m, 8.35s. 8.5s, 8.8m, 10.45m, 13.4w,15.0w microns Anal. Calc'd. for C H F C, 37.5; H, 3.13; F, 59.4 Found:C, 37.2; H, 3.45; F, 60.1

The approximate ratio of the cis to trans isomer in this product is 1:1.The boiling point range of the dimer product is 84 to 90C., with thecis-isomer being the higher boiling component. Other important physicalproperties of the l-trifluoromethyl-l,2,2'trifluoro-4- methylcyclobutaneare:

1. Critical Temperature 250.3 1- 5C. 2. Liquid density (g/ml) 1.37911.9174Xl0 t 236C. 5 t s 150.3C. (1.3312 at 25C.) Liquid density (g/ml)4.8407 5.9063Xl0' t 3.l70 l0t 5.9748 l0"t 155C. 5 t s 239.8C. 3. Sat.vapor density (g/ml) 7.l963 l0 t 5.6973 10" t"+1.515 l0"t 0.28585100.2C.

s t 239.8C. 4. The mean vapor and liquid density (d d,.,,,,)/2 0.6980969.6679 l0 *t 23.6 s t s 250.3C. 5. The critical density is estimated tobe 0.456 g/ml. 6. The index of refraction, n is L3 7. Three purifiedsamples gave liquid dielectric constants= 17.8. 19.1, and 19.5 withdissipation factor less than 10'. Average 18.8. 8. Vapor press isapproximated by the relationship.

log p 7.85650 l783.53689/TK 9. Glass point= l30C. 10. Liquid range=220C. Also produced in low yield by the above reaction and isolated bygas chromatography from a forecut of the cyclic adduct distillation arethe novel ethylenic monomcr CH =CHCH CF CFHCF and the internallyunsaturated product CH CH=CHCF,CFHCF These structures are confirmed bytheir proton and F nmr spectra. This data is given below for neatsamples, as obtained with external standards; trifluoroacetic acid for Fand 5% tetramethylsilane in chloroform.

ization which can be induced in a molecule is a sum of the polarizationwhich can be induced in the electron cloud of the molecule (P and thatwhich can be induced through atomic polarizations (or atom displacementswithin the molecule) (P In general, the small P, amounts to only 540% ofthe value of P for radiaumpound Group Bands Center (ppm) (oupling conststH CF Double quartet 126 J, 9.

Juc 5.4 (bl F 1d) (e) to (g) C F;,-(C F CH CH=CH CF AB system withfurther 32.75 Jgem 269. chem shift (a) couplings of 1. ppm,

(.F Double sextuplet [34.83 Jbc '4! (H Triplet, each component a 2.36.lde l7.5

doubled doublet Jcl- 5.5 (.H, (omplcx 4.7l 5.88 CHM) (omplexapprox. adoubled 4.37 .lbc 47 sextuplel CF, Double quartet --2.2X J 1 It) J2 h(b) F 1 (dl (e) (n (g) CF;;C(TF CH=CHCH; CF-, AB system with further282, 32.9 Jgem= 267, chem, (a) couplings 35.2. 39,9 shift of 5.2 ppm,

H ICI CF Double sextuplet [33.3 Jht- 41 CH;, Singlet L56 CH=CH Twosinglets 5.08. 5.l8 ("H umplex, approx. a double 4.5] l,,, 1 46scxluplet The very low glass point and relatively high boiling point ofthe cyclic adduct of this invention gives it valuable utility as aworking fluid for hydraulic systems and as a heat transfer fluid over awide operable range of temperatures, especially as compared to thecyclic dimer of hexafluoropropene which freezes at only C., and Coffmanet als cyclic adduct of tetrafluoroethylene and propylene which boils atjust 68.5C. The molar refractivity of the TFE/C H adduct is 23.5 andthat for the HFP/C H adduct can be calculated from the experimental databy the relation,

MRI): ["0 "T 1/"0 where MR and n are, respectively, the molarrefractivity and the index of refraction for light at the wavelength ofthe sodium- D line (5,890 angstroms), M is the molecular weight, and pis the density. Therefore, the molar refractivity is The average atomicrefraction of the fluorine atom given by Coffman, et al. (Loc. cit.) asl.08 is in error and should be 1.21. This is important only in comparingthe experimental data. Using the (corrected) value of atomic refractionof Coffman et a1. (Loc. cit), the theoretical value based upon theadditivity of the atomic refractions (see S. Glasstone, Textbook ofPhysical Chemistry, 2nd Ed., p, 530) is 28.4. This agreement between themolar refractivity calculated from the expermimental data and thatcalculated from the additivity of atomic refractions is very good, andconfirms the experimental data.

The cyclic dimer of the invention is further distinguished from thetetrafluoroethylene-propylene adduct by its polarizability which can becompared from calculations based on the molar refraction. The totalpolar tion in the region of the sodium-D line. Light is anelectromagnetic phenomenon and it is therefore not surprising that thereis a relation between the molar refractivity and the total polarizationwhich can be induced in a molecule,

MR [nfi-l/m, 2]- M/p= P (Glasstone: loc. cit., R537) Therefore a ratioof the molar refractivities of two compounds should indicate therelative polarization which can be induced in the two molecules.

MR for HFP/C H IMR for TFE/C H =28.2/ 23.5= 1.20

The HFPlC l-l. adduct is about 20% more polarizable than the TFE/C Hadduct and therefore a better solvent for polar, or ionic, solutes. Inaddition, the HFPlC H adduct is thus a better solvent for organicreactions involving electron displacements. Conversely, the HFP/C Hadduct is a poorer solvent for purely covalent molecules than the TFE/Cl-l adduct, a property that can be used to advantage in working fluidapplications.

In addition, the unexpectedly high dielectric constant l7l 9) of the newdimer also gives it utility as an inert, non-functional solvent forfluoropolymer molecular weight determinations and fluorochemicalreactions. The dielectric constant is of the same order as pyridine(12.3) and acetone (20.7), two commonly used reaction and cleaningsolvents. A much lower value of the dielectric constant would bepredicted, however, because a range of about I to 7 (vapor and liquiddata) is obtained for such compounds as CClF CF CI CHCl F, CHClF CH CF(a compound having the same ratio of H/F as the new compounds), CH CCIFCF CH CI, and CCl FCClF Solvents effects are demonstrated by the factthat acetone and ethanol are only slightly soluble in hexafluoropropenedimer, but are completely soluble in the new mixed dimer.

Further insight into the solvent properties is gained by a considerationof the dipole moment of the cyclic HFP/C l-l adduct which may beestimated from the measured dielectric constant. The total polarizationof any molecule at any instant in time is due to two factors: l l thetotal polarization which can be induced in the molecule by an electricalfield (P and (2) the polarization which is inherent in the moleculebecause of its structure P The relation between the total polarizationat any instant and the dielectric constant is given by the relation PP,, Dl/D+2' M/p The value for P,, may be obtained from P,, P P l.l P l.lMR,,= 31.02, and from the relation where N Avogadro's number, 6.02 Xmolecules/mole,

k R/N Boltzmanns constant,

R 8.3 l4 X ergs/mole/deg.,

T absolute temperature. and

p. dipole moment of the molecule,

It can be estimated that the dipole moment, ,u. is 2.13 X l0" e.s. unitcm. or 2. l 3D. This relatively large dipole moment (acetone is 2.7,butylamine is 1.4, and

water is L84) implies a polar molecule and is evidence that the HFPlC Hadduct has unusual solvent proper ties.

The linear adducts herein. CH =CHCH,CF,CFHCF and cH CHiHCF cFHcF areuseful as comonomers in the preparation of ethylene and propylenepolymers in amounts of up to about 20% by weight of the ethylene orpropylene copolymer which is prepared by conventional polymerizationtechniques well known for the production of olefin polymers. Thefluorinated comonomer gives the ethylene or propylene polymer bettermechanical processing characteristics (improved extrudability andmoldability), flame resistance, and in creased resistance to solvents.The terminally unsaturated compound is the more preferred fluorinatedcomonomer because of its greater reactivity in the polymerization.

We claim:

I. A compound of the structure embodied (T F2C F-C F1 (HI (.H CHH 2. Amixture of cisand trans-I-trifluoromethyl- I,2,2-trifluoro-4-mcthylcyclobutane.

2. A mixture of cis- andtrans-1-trifluoromethyl-1,2,2-trifluoro-4-methylcyclobutane.